Abstract

Homegardens are social-ecological systems that play a multifunctional role in providing food while sustaining agrobiodiversity and ecosystem processes. Social-ecological factors can act as filters of plant species' functional traits and thus influence the species richness-functional diversity relationship in homegardens. We tested the species richness-functional diversity relationship of plant communities and examined how small-scale farmers' sociodemographic profiles, cultural practices, and management strategies act as social-ecological filters in homegardens of the southern Andes, Chile. Between 2016 and 2020, we surveyed 100 small-scale farmers and sampled their homegardens (50 tendered by campesinos and 50 by migrants). We recorded 284 cultivated species and 544 ethnovarieties. Homegardens tended by lifestyle migrants had a higher total plant species richness (243 species vs. 206) but, on average, campesino homegardens exhibited greater species richness (36.7 +/- 13.2 vs 32.9 +/- 19). We found a positive relationship between species richness and functional richness that saturated in homegardens with a high level of species richness, indicating functional redundancy in speciesrich homegardens. Gardener participation in seed exchanges (yes/no), homegarden age (years), homegarden area (m2), pest control strategy (natural, chemical, or none), and gardener origin (campesino or migrant) were the most influential social-ecological filters selectively removing plant species, and thus influencing both taxonomic and functional diversity. We discuss opportunities in homegarden management for strengthening functional agrobiodiversity and resilience in the face of rapid social-ecological changes occurring across spatial and temporal scales.